Chapter 7

The Working Cell:

Energy from Food

Do Now

What do plants need to make sugar?What do animals get from plants?

7.1 Sunlight Powers Life

FoodWater CycleClimate

Why is the sun important to life?

Autotrophs autotroph: organism that

makes its own food: “self-feeder” Inorganic materials --> organic

materials photosynthesis: uses the su

n’s energy to convert to food Light(energy) + water + CO2 --

> sugar + O2

producers: produce organic molecules that serve as food for other organisms in the ecosystem

Heterotrophs

heterotrophs: organisms that can’t make food; “other eaters”

consumers: must obtain food by eating producers or other consumers depend on producers for

energy and materials for life and growth

Cellular Respiration

cellular respiration: chemical process that uses oxygen to convert the chemical energy stored in organic molecules into another form (ATP)food into energy

C6H12O6 + O2 --> H2O + CO2 + energy

Do Now

Take out your homework (7.1 & 7.2 CC)

HW: 7.3 CC

What is the equation for cellular respiration?

7.2 Food Stores Chemical Energy

energy: the ability to perform work

kinetic energy: the energy of motion

potential energy: energy stored due to an object’s position or arrangement gain potential energy the higher

you go against gravity thermal energy: random

molecular movement which causes collisions and heat energy used is provided by food

Chemical Energy

Chemical energy the potential to perform

work is due to the arrangement of atoms within the molecules

depends on the structure of the molecules

(carbs, fats, and proteins are rich in chemical energy)

sugar (high potential) carbon dioxide + water (kinetic energy)

Cellular Respiration is like a Car Engine

high chemical energy = glucose and oxygen (gasoline and oxygen)

“exhaust” = carbon dioxide and water

40% from food to work 60% thermal energy as heat =

100W light bulb calorie: amount of energy

required to raise the temperature of 1g water by 1 degree Celsius 1000 calories = 1 kcal = C (on food labels)

Do Now

Take out your homework4 people at a time take the survey on

the computers in the backhttp://www.surveymonkey.com/s/

59F79KY

7.3 ATP

ATP: adenosine triphosphate Adenosine = adenine + ribose Triphosphate = 3 phosphates

One phosphate is lost in a chemical reaction ATP --> ADP The molecule that accepts the phosphate undergoes a change (for work)

Work chemical work: building large

molecules Ex. Proteins ATP energy for dehydration

synthesis links AA mechanical work: contraction

of muscle ATP transfers P to proteins -->

change shape --> muscle cells contract

transport work: pumping solutes (ions) across a cellular membrane P --> change shape

ATP CycleATP is continuously

converted to ADPMuscle cell recycles

all ATP once a minute

10 million spent and regenerated per second

Do Now

What is the overall purpose of cellular respiration?

Homework: Work on video critique lyricsQuestions 1-12 on CR worksheet

Food to Oxygen

Relationship of Cellular Respiration to Breathing

aerobic: process that requires oxygenETC

Anaerobic: does not require oxygenGlycolysisfermentation

In Cellular Respiration…

Oxygen attracts electrons very strongly “electron grubber”

Carbon and hydrogen exert much less pull Several carbon-hydrogen bonds in sugar

Carbon and hydrogen change partners and bond with oxygen Electrons in these bonds “fall” toward oxygen and release energy

Ex. Burning sugar

7.5 CR Converts Energy

Mitochondria Envelope of 2 membranes;

inner and outer with space Inner membrane encloses

thick fluid (matrix) Enzymes and other

molecules built into inner membrane

Complex folding allows many sites of reactions to maximize ATP production

Metabolism

metabolism: a cell’s chemical processes

Metabolic PathwaySeries of reactionsSpecific enzymes

catalyzes each reaction

3 Stages of CR Glycolysis, Kreb

cycle, ETC and ATP synthase

Stage 1: Glycolysis “splitting of sugar”

Outside the mitochondria in the cytoplasm

1. 2 ATP molecules split a 6-carbon glucose in half and adds a phosphate to each C-C-C-P

2. Each 3-C molecule transfers electrons and H+ to a carrier molecule NAD+

3. NAD+ accepts 2 electrons and one H = NADH

4. “payback” = 4 new ATP molecules produced5. Result is 2 pyruvic acid molecules

Cycle Input Output ATP

Glycolysis Glucose Pyruvic acid

2

Krebs Acetyl CoA

(from pyruvate)

CO2 2

ETC Electrons, O2 H2O 34

Overall C6H12O6 + O2 CO2 + H2O +38

Stage 2: Krebs Cycle (Hans Krebs)

Finishes breakdown of pyruvic acid molecules to CO2 which releases more ATP Enzymes are dissolved in

the fluid matrix Pyruvic acid does not

take part in the Krebs cycle Diffuses into the

mitochondrion and loses a molecule of CO2

Converted to a 2-C compound = acetyl CoA (Acetyl coenzyme A )

Krebs Cycle Steps

1. Acetyl CoA molecules joins a 4-C acceptor molecule

2. Produce 2 more CO2 molecules and an ATP per acetyl CoA

3. NADH and FADH2 trap most of energy

4. The 4-C acceptor regenerates and cycle continues

Cycle Input Output ATP

Glycolysis Glucose Pyruvic acid 2

Krebs Acetyl CoA CO2 2

ETC Electrons, O2 H2O 34

Overall C6H12O6 + O2 CO2 + H2O +38

Stage 3: ETC and ATP Synthase

1. NADH transfers electrons from glucose to ETC

2. Each transfer in the chain releases energy which is used to pump H+ across the membrane Less concentrated to more Stores potential energy

ATP synthases: protein structures in mitochondria that act as miniature turbines

3. H+ rush back “downhill” through the ATP synthase Energy used to convert ADP to ATP

Cycle Input Output ATP

Glycolysis Glucose Pyruvic acid 2

Krebs Acetyl CoA CO2 2

ETC Electrons, O2 H2O 34

Overall C6H12O6 + O2 CO2 + H2O +38

Summary of Cellular Respiration

7.6 Fermentation fermentation: process that can make ATP without oxygen (only 2 ATP) anaerobic: environment without oxygen Fermentation makes ATP entirely from glycolysis

Not enough oxygen being supplied Produces waste product called lactic acid

Temporary build-up results in soreness & fatigue Eventually converts back into pyruvic acid

Fermentation in Microorganisms and plants

Yeast is forced to ferment sugar Produces alcohol and CO2, not lactic acid

Some fungi and bacteria produce lactic acid Transform milk into cheese and yogurt

Oxygen allows most energy from food Much more efficient 38 ATP (w/oxygen) vs. 2 ATP (w/out)